Health effects following long-term exposure to thorium dusts: a twenty-year follow-up study in China

Abstract

A twenty-year follow-up study was carried out at Baiyun Obo Rare-earth Iron Mine in China, This mine has been mined since 1958. Its ore contains 0.04% of ThO 2 and 10% of SiO 2 . The purpose of this study is to investigate possible health effects in dust-exposed miners following long-term exposure to thorium-containing dusts and thoron progeny. By using the negative high voltage exhaled thoron progeny measurement system to estimate the miner's thorium lung burden. The highest thorium lung burden among 1 158 measurements of 638 miners was 11.11 Bq. The incidence of stage 0 + pneumoconiosis was increased among dust-exposed miners. An epidemiological study showed that the lung cancer mortality of the dust-exposed miners was significantly (p < 0.005) higher than that of the non-exposed group. It is suggested that the difference results in the long-term exposure to thorium-containing dusts (carcinogens are ThO 2 and SiO 2 ) and thoron progeny. This is the first evidence in humans of the carcinogenicity after long-term inhalation of thorium-containing dusts and thoron progeny. The total person-years of observation for the dustexposed miners and the controls were 62 712 and 34 672 respectively. (1993.12.15-1994.12.15), a project from IAEA Project no. 11526 RBF (2000RBF ( .12.15-2001 RÉSUMÉ

The Variation with Age of 67 Macro- and Microelement Contents in Nonhyperplastic Prostate Glands of Adult and Elderly Males Investigated by Nuclear Analytical and Related Methods

“…In addition to the elevated Zn level, an age-related increase and excess in Ba, Bi, Cd, Co, Fe, Hg, Pb, Sc, Sn, Th, and U mass fractions in prostatic tissue may contribute to harmful effects on the gland. There are good reasons for such speculations since many reviews and numerous papers raise the concern about toxicity and carcinogenicity of these metals [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85]. Each of these metals is distinct in its primary mode of action.…”

Combined Thermodynamic, Theoretical, and Biological Study for Investigating N-(2-Acetamido)iminodiacetic Acid as a Potential Thorium Decorporation Agent

“…7−16 A study reported pneumoconiosis and lung carcinogenesis in Chinese miners due to long-term inhalation of Th-containing dust (average Th in lung, 0.4 mg). 17,18 Th is mainly deposited in the liver, bone, and lungs and produces carcinogenic events due to its long retention time (biological half-life of ∼5−20 years). 19,20 Studies have reported cancers of the liver, lung, pancreas, spleen, bone, and blood due to high levels of exposure to Th.…”

“…A study reported pneumoconiosis and lung carcinogenesis in Chinese miners due to long-term inhalation of Th-containing dust (average Th in lung, 0.4 mg). , Th is mainly deposited in the liver, bone, and lungs and produces carcinogenic events due to its long retention time (biological half-life of ∼5–20 years). , Studies have reported cancers of the liver, lung, pancreas, spleen, bone, and blood due to high levels of exposure to Th. , Besides the major retention of Th in the skeleton (70%) and liver (5%), a significant amount of Th is also absorbed in the blood, out of which 10% is readily soluble, while the other 90% of Th gets associated with the blood cells, suggesting one of the major fractions of Th important for decorporation by chelation therapy. , …”

Novel Harmless Utilization of Bayan Obo Tailings: Separation and Recovery of Iron and Rare Earth

“…Besides RE and Fe, the Bayan Obo tailings contain other elements such as fluorine, radioactive thorium, niobium, scandium, phosphorus, etc. Among them, some elements pose a threat to human health, such as fluorine and radioactive thorium, as well as RE. − The tailing dam is near the Yellow River, the second longest river in China, causing serious environmental pollution ,,− and the potential risk of dam breakage. Therefore, the tailings disposal attracts great attention from the government and scientists.…”